Q. For what distance is ray optics a good approximation when the aperture is $4mm$ wide and the wavelength is $500\ nm$
A) $32\ m$
B) $64\ m$
C) $16\ m$
D) $8\ m$
Explanation
(a) Fresnel distance $Z_{F} = \frac{a^{2}}{\lambda} = \frac{\left( 4 \times 10^{- 3} \right)^{2}m^{2}}{500 \times 10^{- 9}m} = 32m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.